Ellefson works with online marketing companies and app developers. He says anything you put on your device and any website or information you access become part of your phone or tablet's historical data and that's what developers and third-party companies are looking for and using.

"If it knows that I search and I've been looking for these types of things or it know my age and the fact that I'm single from my Facebook profile, because I've given it that, it can start serving me up ads that it thinks is appropriate to the device, not necessarily to the child based on the app that they're using," Ellefson said.

So while most parents think child-appropriate apps should come with age-appropriate ads, it doesn't always work that way. Ellefson says parents need to know what they are handing their children. He suggests playing with the app yourself and reading all of the fine print before letting your little one play.

"We live in a fast-paced world. A lot of times we scroll right past all of those disclaimers that are available on every single app that you download that you show exactly what information you are allowing that app to glean off your phone," Ellefson said.

In the next few weeks, the Federal Trade Commission hopes to toughen up the Children’s Online Privacy Protection Act regarding what types of information can be extracted from your phone or mobile tablet. The current law was written in 1998 before smartphones and mobile tablets existed.